<!DOCTYPE html>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<title>粒子线条canvas效果</title>
	<style>
		body {
			background-color: #292929
		}

		#J_dotLine {
			display: block;
			margin: 0 auto;
		}
	</style>
</head>

<body>
	<!--
		**canvasAPI
			https://developer.mozilla.org/zh-CN/docs/Web/API/Canvas_API
		**大神教程
		1、http://www.cnblogs.com/axes/p/4960171.html
	 -->
	<canvas id="J_dotLine" style="background-color: #F7F7F7;"></canvas>
	<script>
		; (function (window) {
			function Dotline(option) {
				this.opt = this.extend({
					dom: 'J_dotLine',//画布id
					cw: 1000,//画布宽
					ch: 500,//画布高
					ds: 100,//点的个数
					r: 0.5,//圆点半径
					cl: '#000',//颜色
					dis: 100//触发连线的距离
				}, option);
				this.c = document.getElementById(this.opt.dom);//canvas元素id
				this.ctx = this.c.getContext('2d');
				this.c.width = this.opt.cw;//canvas宽
				this.c.height = this.opt.ch;//canvas高
				this.dotSum = this.opt.ds;//点的数量
				this.radius = this.opt.r;//圆点的半径
				this.disMax = this.opt.dis * this.opt.dis;//点与点触发连线的间距
				this.color = this.color2rgb(this.opt.cl);//设置粒子线颜色
				this.dots = [];
				//requestAnimationFrame控制canvas动画
				var RAF = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function (callback) {
					window.setTimeout(callback, 1000 / 60);
				};
				var _self = this;
				//增加鼠标效果
				var mousedot = { x: null, y: null, label: 'mouse' };
				this.c.onmousemove = function (e) {
					var e = e || window.event;
					mousedot.x = e.clientX - _self.c.offsetLeft;
					mousedot.y = e.clientY - _self.c.offsetTop;
				};
				this.c.onmouseout = function (e) {
					mousedot.x = null;
					mousedot.y = null;
				}
				//控制动画
				this.animate = function () {
					_self.ctx.clearRect(0, 0, _self.c.width, _self.c.height);
					_self.drawLine([mousedot].concat(_self.dots));
					RAF(_self.animate);
				};
			}
			//合并配置项，es6直接使用obj.assign();
			Dotline.prototype.extend = function (o, e) {
				for (var key in e) {
					if (e[key]) {
						o[key] = e[key]
					}
				}
				return o;
			};
			//设置线条颜色(参考{抄袭}张鑫旭大大，http://www.zhangxinxu.com/wordpress/2010/03/javascript-hex-rgb-hsl-color-convert/)
			Dotline.prototype.color2rgb = function (colorStr) {
				var red = null,
					green = null,
					blue = null;
				var cstr = colorStr.toLowerCase();//变小写
				var cReg = /^#[0-9a-fA-F]{3,6}$/;//确定是16进制颜色码
				if (cstr && cReg.test(cstr)) {
					if (cstr.length == 4) {
						var cstrnew = '#';
						for (var i = 1; i < 4; i++) {
							cstrnew += cstr.slice(i, i + 1).concat(cstr.slice(i, i + 1));
						}
						cstr = cstrnew;
					}
					red = parseInt('0x' + cstr.slice(1, 3));
					green = parseInt('0x' + cstr.slice(3, 5));
					blue = parseInt('0x' + cstr.slice(5, 7));
				}
				return red + ',' + green + ',' + blue;
			}
			//画点
			Dotline.prototype.addDots = function () {
				var dot;
				for (var i = 0; i < this.dotSum; i++) {//参数
					dot = {
						x: Math.floor(Math.random() * this.c.width) - this.radius,
						y: Math.floor(Math.random() * this.c.height) - this.radius,
						ax: (Math.random() * 2 - 1) / 1.5,
						ay: (Math.random() * 2 - 1) / 1.5
					}
					this.dots.push(dot);
				}
			};
			//点运动
			Dotline.prototype.move = function (dot) {
				dot.x += dot.ax;
				dot.y += dot.ay;
				//点碰到边缘返回
				dot.ax *= (dot.x > (this.c.width - this.radius) || dot.x < this.radius) ? -1 : 1;
				dot.ay *= (dot.y > (this.c.height - this.radius) || dot.y < this.radius) ? -1 : 1;
				//绘制点
				this.ctx.beginPath();
				this.ctx.arc(dot.x, dot.y, this.radius, 0, Math.PI * 2, true);
				this.ctx.stroke();
			};
			//点之间画线
			Dotline.prototype.drawLine = function (dots) {
				var nowDot;
				var _that = this;
				//自己的思路：遍历两次所有的点，比较点之间的距离，函数的触发放在animate里
				this.dots.forEach(function (dot) {

					_that.move(dot);
					for (var j = 0; j < dots.length; j++) {
						nowDot = dots[j];
						if (nowDot === dot || nowDot.x === null || nowDot.y === null) continue;//continue跳出当前循环开始新的循环
						var dx = dot.x - nowDot.x,//别的点坐标减当前点坐标
							dy = dot.y - nowDot.y;
						var dc = dx * dx + dy * dy;
						if (Math.sqrt(dc) > Math.sqrt(_that.disMax)) continue;
						// 如果是鼠标，则让粒子向鼠标的位置移动
						if (nowDot.label && Math.sqrt(dc) > Math.sqrt(_that.disMax) / 2) {
							dot.x -= dx * 0.02;
							dot.y -= dy * 0.02;
						}
						var ratio;
						ratio = (_that.disMax - dc) / _that.disMax;
						_that.ctx.beginPath();
						_that.ctx.lineWidth = ratio / 2;
						_that.ctx.strokeStyle = 'rgba(' + _that.color + ',' + parseFloat(ratio + 0.2).toFixed(1) + ')';
						_that.ctx.moveTo(dot.x, dot.y);
						_that.ctx.lineTo(nowDot.x, nowDot.y);
						_that.ctx.stroke();//不描边看不出效果

						//dots.splice(dots.indexOf(dot), 1);
					}
				});
			};
			//开始动画
			Dotline.prototype.start = function () {
				var _that = this;
				this.addDots();
				setTimeout(function () {
					_that.animate();
				}, 100);
			}
			window.Dotline = Dotline;
		}(window));
		//调用
		window.onload = function () {
			var dotline = new Dotline({
				dom: 'J_dotLine',//画布id
				cw: 1000,//画布宽
				ch: 500,//画布高
				ds: 100,//点的个数
				r: 0.5,//圆点半径
				cl: '#12FC41',//粒子线颜色
				dis: 100//触发连线的距离
			}).start();
		}
	</script>
</body>

</html>